The invention relates generally to radiofrequency (RF) coils for use in Magnetic Resonance Imaging (MRI) and more particularly, the invention relates to RF coils for use in MRI systems employing multiple receiver channels.
MRI systems employing multiple receiver channels allow for simultaneous acquisition of image data, and thus enable a reduction in acquisition time, that is desirable in a number of clinical applications. In order to obtain image data using a multiple receiver coil configured MRI scanner, a corresponding number of RF coils are assembled and each RF coil is coupled to a respective receiver channel. Currently, multiple RF coil assemblies are constructed as an array, such that each RF coil in the array is placed close to the anatomy of interest. Arrays can be constructed to provide optimal imaging for the chest, pelvis, head or other parts of the body.
In a typical multiple coil array arrangement, several adjacent coils are provided for receiving signals during imaging. However, there are a number of design challenges in providing the capability of multiple receive channels and multiple coils. For example, the size of coils needed to support a multi-channel MRI system must be sufficiently small to fit within a typical 40 cm field of view of a conventional MRI system, or a smaller field of view for some applications. Additionally, the coil size and corresponding arrangement within a coil array will present with inherent inductive coupling and sensitivity issues which both can negatively impact the quality (Q) factor and loading factors of the coils, thereby limiting overall signal-to-noise ratio (SNR) performance of the coils and MRI system during imaging. The Q factor is an important indication of the RF coil sensitivity to induced currents in response to signals emanating from the subject or patient being imaged. Further, the patient “loading” effects, eddy currents among other things, can cause coil losses that lead to lower SNR.
Thus, there is a need a for highly coupled RF coil assembly having high Q and high loading factor MRI coils for use in a multi-channel MRI system